Large recreational vehicles often require one or more high capacity roof mounted air conditioners in order to maintain the interior space of the R.V. at comfortable temperatures for the occupants. The present invention is directed toward increasing the cooling effect of roof mounted air conditioners of the type used on R.V.'s that have the condenser air intake oriented or directed toward the rear of the R.V. The inventor hereof has noticed that air conditioners of this type have a marked decrease in cooling effect during periods during in which the R.V. is traveling at speeds in excess of thirty (30 mph) miles per hour. Because of this marked decrease in cooling effect when traveling at speeds in excess of thirty miles per hour in hot climates, it is necessary to either make stops along the way to allow the air conditioner to lower the temperature within the R.V. or to run a second roof mounted air conditioner unit. It would be a benefit, therefore, to have a device for increasing the cooling effect of roof mounted air conditioners of the type used on R.V.'s that have the condenser air intake oriented or directed toward the rear of the R.V. while traveling at speeds in excess of thirty miles per hour without reducing the cooling effect of the unit while parked or traveling at speeds below thirty miles per hour. It would be a further benefit if the device were easily installed on existing roof mounted air conditioner units and did not require special training and/or specialized equipment to make the installation. It would be a still further benefit if the device were inexpensive to operate and maintain.